Food allergy or food intolerance - are allergies being over-diagnosed?

Food allergy or food intolerance - are allergies being over-diagnosed?

Research homes in on the spike of diagnoses and the possibility of adverse health trends …

Oh, I can’t eat that. I have an allergy.

There’s no doubt about it, it’s become increasingly common to bump into someone who mentions a food allergy of some kind.

Food and its variety of popular intolerances has been on the rise in recent years, prompting a range of diets that vary from downright fad to scientifically researched, albeit sometimes controversially.

Those in the medical field have noted this spike and it’s made people sit up and ponder as to why. As such, research into why more and more people are developing allergies and intolerances is underway.

Some are now wondering if indeed, food allergies are being misinterpreted left, right and centre and being over-diagnosed. Or are food allergies just over-reported prompting many to shift their diets based on the assumption they have an allergy, and unnecessarily avoiding certain foods?

During the past two decades, the CDC (Centers for Disease Control and Prevention) estimated that food allergies in adults alone rose by as much as 50% and 18% among children (in the USA). That’s as many as 15 million individuals with food allergies in the United States of America alone (enough to make anyone gasp).

In 2015, a report from the FDA (Food and Drug Administration) in the USA also released findings from research conducted between 2001 and 2010 that also showed considerable increases in reported food allergies in adults and children. Spikes increased from 9.1% to 13%. The study also stepped into areas of assumption… Does the general public just make assumptions about food allergies, without ever getting a medically approved test?

The answer is yes. Among the participants, only 28% of those who maintained they or their children had food allergies actually tested positive. This raises alarm bells. How many people are cutting out healthy foods from their diets and thus, causing negative implications on their own state of health?

Factors that have experts rallying for further investigation include lifestyle, genetics and various environmental influences. Are these factors reasons for the spike in allergies to food?

Experts aren’t all on the same page. Some argue the theory that cases of actual food allergies have not spiked. Over-diagnosis and over-reporting are being identified as the reasons for a growing number of misconceptions. Another question mark hangs over the possibility of inaccuracy when it comes to testing. Food allergies and food intolerances are not the same thing.

What is the difference?

Anyone with a food allergy will tell you that it’s not something to take lightly. For them, it could very well mean the difference between life and death. So, why are there blurred lines in the definitions between allergies and intolerances?

A food allergy

Peanut butter on bread with red crayon warning against peanuts.In a nutshell, a food allergy is a medically classified condition as a result of adverse reactions to specific food compounds in the body’s immune system.

Allergist, Dr David Stukus from the American College of Allergy, Asthma and Immunology (ACAAI) says that are a total of 8 known foods that are behind approximately 90% of all recorded food allergies. Allergen foods include milk, eggs, tree nuts, peanuts, wheat, soy, shellfish and fish.

Adverse reactions (symptoms) to these foodstuffs can be both mild to more serious (severe). Reactions include things like problems with the ability to breathe, wheezing, coughing, tongue swelling, a decline in blood pressure, dizziness, stomach cramps (pain), vomiting, hives and itching of the skin.

The most serious reaction that typically require emergency treatment is anaphylaxis (pronounced an-a-fi-LAK-sis). Essentially, the immune system overreacts to an allergen (compound), releases chemicals that lead to allergic reactions in multiple areas of the body, at the same time. A reaction of this kind is regarded as an emergency, requiring life-saving medical treatment as soon as possible.

A food intolerance

It’s possible that confusion about the difference between food allergies and intolerances relates to the experience of similar symptoms, which are triggered by certain foodstuffs.

The distinctive differences relate to severity and the direct reaction cause. Overreaction occurs in the GI tract (gastrointestinal tract) and not the immune system, as is the case with an allergy. As such symptoms of stomach or abdominal pain, bloating, vomiting and even diarrhoea occur as a result. Symptoms are normally directly related to the amount of food that is ingested at the time.

A food intolerance is not known to be life-threatening at all. It’s merely a discomfort. One example is a person who is lactose intolerant. The body simply does not have enough lactase (an enzyme in the intestine which effectively breaks down lactose). A lack of this enzyme means that lactose is unable to be properly digested in the body. The result is symptoms of gastrointestinal distress.

Woman with hand on her stomach, holding a glass of milk

Outlining the theories being researched

There are a number of theories on the table when it comes to distinguishing between the two adverse reactions to food and whether or not there is a distinctive spike in cases across the world.

What causes food allergies? For experts researching this, precise causes are not entirely known. In the research process, theories are being looked at with a fine-tooth comb. Is there a lack in how allergies are being screened? Is one screening method better and more accurate than another? Are there other factors that potentially need to be made more of a priority when considering a possible allergy?

Theory – Peanuts

Dr Stukus believes that the current guidelines which do not recommend an introduction of such foodstuffs to toddlers until at least 2 years of age may in fact be the reason for a reported rise in associated allergies.

His thinking supports recent research which has shown that earlier introduction to children considerably reduces the development of an allergy to peanuts. Introducing peanuts to a young child by the time they are 12 months instead of, at the latest, 3 years of age could decrease the number of allergies diagnosed.

Theory – “Hygiene hypothesis”

Related to the theory concerning peanuts, the Hygiene hypothesis centres around the notion that exposure levels to various pathogens (bacterium, viruses, or other microorganisms that cause medical conditions and diseases) early enough in life is low and possibly making new generations more prone to food allergies.

It is true that the hygiene habits of the broader population worldwide have changed dramatically in the last 30 to 100 years. Food processing, dishwashing and even bathing methods are different now than what they used to be. Also, new medications in use, as well as how we engage with or live with animals has also significantly changed.

Dr Stukus notes that there has been a considerable increase in antibiotics prescribed to children, as well as the use of antibacterial sanitisers and soaps which are shifting differences in our microbiomes (i.e. our bodies). Dr Stukus doesn’t regard these factors as direct causes, but merely associated influences whereby significant increases in occurrences are linked to possible spikes in developing allergies.

A recent study, published in 2016, determined that children with higher levels of antibiotic use showed a distinct difference in the balance of natural gut bacteria, and as such appeared at higher risk of developing food allergies.

Theory – Over-diagnosis

Skin prick test - to determine a kind of allergyIs testing actually more of a problem, promoting misconceptions? Another theory on the table has some experts believing that the idea of inaccurate testing and over-diagnosis are likely fuelling the spike.

When it comes to testing for food allergies, skin pricks have come under fire as being ‘inaccurate’. Allergists usually begin their evaluations by conducting a medical interview with a patient and discussing the causes for concern. This includes a history of symptoms and assessing a person’s overall health.

From there a skin prick test is done. If a specific foodstuff is suspected, a very small amount of the food allergen is placed on the person’s back or forearm using a plastic probe or needle. The person will then be monitored for a possible reaction within a set period of time.

Blood tests may also be ordered as part of the diagnostic process. A sample of blood is taken and immunoglobulin E (IgE) antibody levels for specific foods are then measured in a laboratory. If levels are high, this typically indicates an allergy. With these results, a person is usually advised to stop consuming certain foods altogether.

So, what’s the concern? A study conducted recently tested participants with a diagnosed (on the basis of a skin prick test) allergy to tree nuts. Their levels of concern increased when it was determined that they experienced no adverse reaction at all after consuming (or ingesting) the ‘feared’ foodstuff.

The argument then begs to prove just how reliable these tests actually are. Dr Jonathan Bernstein, at The American Academy of Allergy, Asthma and Immunology (AAAAI) says that he views the skin prick test as perhaps only really reliable enough for diagnosis about 60% of the time.

An allergy, in a nutshell, is a sensitive reaction displaying clinical symptoms as a result of specific exposure factors. Dr Bernstein believes that it shouldn’t be that an allergy is assumed based on this test and that possibly, these tests are under-developed, requiring more accuracy. Dr Stukus appears to agree that this test alone is not conclusive enough to make a diagnosis.

Theory – “Oral food challenges" under-used
The go-to testing procedures for allergies are the skin prick and blood sample tests. Another option available for diagnosis is ‘oral food challenges’. Many regard this as the “gold standard” for diagnosis, and yet this test is not as commonly used in making a diagnosis for food allergies. Rather, professionals will try and assess how soon a person experienced a reaction after ingesting a specific food through discussion as a way to differentiate between an allergy and an intolerance, instead of performing an oral food challenge.

So, what is it? An oral food challenge is when a person is given suspected allergy-causing foodstuff, and under strict medical supervision is monitored after it has been ingested. Varying doses are given to determine whether the suspected food triggers any adverse reactions. It is important to vary doses, for both allergies and intolerances as reactions may differ.

If eaten, a food allergen should trigger a reaction directly. If not, the foodstuff may merely signify an intolerance or sensitivity.

The nature of the test is likely a fearful one for doctors and allergists to resort to. Many typically, use this means of testing when the blood sample and skin prick test appears inconclusive. The fear is justified. A patient may experience a severe, possibly life-threatening reaction.

Dr Stukus feels that the test has become safer to perform when board certified allergists with sufficient training are on hand to treat an adverse reaction of any nature, should it happen in the monitoring process. He maintains that this method of testing is considerably under-used and since it is far more accurate for making a diagnosis, it should possibly be preferred by medical professionals over the blood and skin prick testing options.

His thinking also suggests that IgE tests are used too broadly as diagnostic tools for screening. Not all positive IgE tests indicate an allergy conclusively. He maintains that a person should not necessarily be told to remove certain foods from their diet immediately based on this screening method alone. A person’s symptom history, the timing of symptoms relating to the consumption of a specific food and the length of the adverse reaction are key factors to take into consideration during the diagnostic process. This will usually help to sift out where in the body a sensitivity originates from – the immune system or the gastrointestinal tract.

So, what should we make of all these theories?

Research is ongoing and experts are still addressing questions relating to the various theories. It’s likely that most will agree that strict restriction of foods should not be happening for mere sensitivities and intolerances. Thus, no assumptions should be made based on “I don’t feel so good when I eat that”. Making such drastic adjustments to your diet could affect your overall health condition and shouldn’t be encouraged.

If you suspect an allergy, you’ll have good reason to. An allergic reaction happens in the short term (within 2 to 3 hours, but more often within minutes) following ingestion of a foodstuff (allergen). Seek medical attention from your primary healthcare provider or an allergist for thorough testing. A full family and medical history should be noted and appropriate tests conducted to determine an actual allergy or just a foodstuff intolerance.